The present invention relates generally to paper slitting machines, and, more specifically, to end-of-roll warning stripes printed therein.
The ubiquitous paper roll is found in various sizes for various applications including cash registers, ATM machines, adding machines, and receipt printers. Each roll typically includes a paper or plastic core around which is wound a continuous ribbon of paper.
Paper rolls are typically produced in a slitting machine in which a large mill roll of paper is mounted at one end of the machine, unwound through the machine, and then slit at numerous locations along its width to provide corresponding ribbons which are then wound on corresponding cores commonly mounted on a supporting arbor or mandrel. The slitting operation is effected by a pair of circular knives or blades which slit the web in a typical shear cut for each of the cores.
In a single production run of paper cores, several cores are mounted coaxially around the supporting arbor in longitudinal abutting contact, and fixedly mounted on the arbor by end fittings or nuts. The arbor is then mounted in the slitting machine.
The slitting blades in the machine are typically arranged in pairs on opposite sides of the paper web with the corresponding cutting or shearing lines thereof being suitably aligned with the respective joints between the cores on the arbor.
In one conventional slitting machine, a row of first circular slitting blades are mounted on a first shaft on one side of the web. The first blades are separated from each other by corresponding precision spacers and thin shims as required to precisely align the cutting edges of the first blades with the corresponding joints between the cores.
A set of second circular blades are pivotally mounted on a second shaft in the machine to selectively engage or disengage the corresponding first blades. Each of the second blades is conventionally mounted in a supporting holder which may be adjusted in position along a supporting dovetail attached to the second shaft. The individual holders may then be adjusted along the dovetail for properly engaging the second blades with their first blade counterparts to control the precise width of each ribbon slit from the web, and also control the cutting overlap or depth between the pairs of first and second blades.
Each production run of paper cores requires the set up of the individual cores on the arbor, alignment thereof with the first blades, and corresponding alignment of the second blades with the first blades, and takes considerable time. Since the first and second blade sets are integral parts of the slitting machine itself, and the arbor must be suitably mounted therein, the slitting machine cannot be operated during the set up procedure which correspondingly reduces the throughput of the machine, and therefore affects cost of operation.
Adding to the set up process for a particular batch run of paper rolls is the alignment required for printing end-of-roll warning stripes. At the commencement of each production run, the leading edge of each ribbon is initially tucked around the empty core and a warning stripe is printed for a short portion of the roll length, for example about three feet. In this way, when the roll is later depleted in use by the user the end-of-roll warning stripe will be visible as the ribbon is dispensed from the printer to alert the user that the paper roll requires changing.
The warning stripe is typically printed in the slitting machine with a suitable color ink in a narrow vertical stripe along one or both edges of the paper roll. This is typically effected by using an inking wick which bridges each of the ribbon slits for simultaneously printing warning stripes along the common slit of the adjoining ribbons. In this way, each ribbon will have a vertical warning stripe printed solely along each edge of the ribbon for the short length of about three feet.
In another conventional slitting machine, the warning stripe may be printed using individual printing rollers which bridge the respective ribbon slits for printing the stripe along the common edges of the ribbons at the slit line. The individual rollers have a hub with a set screw that permits their lateral adjustment along the length of a common supporting shaft.
In either configuration, the printing wicks or the printing rollers must be individually aligned with the respective slit lines for the intended width of the individual rolls to be produced. The typical mill roll has a width of about 53.5 inches, and 11 to 35 rolls may be formed depending upon the standard width thereof. And, the required alignment procedure to print the warning stripes along the several slit lines increases the down time of the machine, and correspondingly increases cost of the paper rolls.
Accordingly, it is desired to provide an improved slitting machine in which downtime for set up of each production run may be minimized for maximizing use of the machine.